SD-365 : Spike: Research async notifications

SD-365 : Spike: Research async notifications

First draft.
SD-365 : Spike: Research async notifications

Finalized with time based notifications pushing.
Merge remote-tracking branch 'gabriel/master'
fix(notifications): start timer only after there are some changes

just to fix the tests, not sure if it's viable
fix(settings): re-enable superdesk.amazon